Buckle for seat belts



May 30, 1967 5M|TH ET AL 3,321,817

BUCKLE FOR SEAT BELTS Filed Jan. 28, 1966 FIG] 2 Sheets-Sheet 1 r 44 :IW

INVENTORS 32 46 GERALD J. PARTIRIDGE w ENC H. s- ITH BY ATTORNEY May 30, 1967 L, H SMITH ET AL BUCKLE FOR SEAT BELTS Filed Jan. 28, 1965 2 Sheets-$heet E GH m w mm O R 0 I AH N P E .E 4 V JC N OH I L R M Y. 8 N NQQ ATTORNEY United States Patent 0 3,321,817 BUCKLE FUR SEAT BELTS Lawrence H. Smith, Bloomfield Hills, and Gerald .1. Partridge, Detroit, Mich, assignors to Jim Robbins Seat Belt Co., Royal Oak, Mich, a corporation of Delaware Filed Jan. 28, 194%, Ser. No. 523,700 8 Claims. (Cl. 224-4341) This invention relates to a buckle for releasably securing the ends of two belt sections of a vehicle safety seat belt system and more particularly to a buckle of the type termed metal-to-metal wherein a male tongue member is secured to the end of one belt and a buckle member secured to the other is adapted to releasably retain the tongue member.

The buckle of the present invention is of the type which automatically locks the tongue in the buckle when the tongue is manually inserted through one side wall thereof and wherein the tongue may be released from the buckle by pressing a pushbutton formed in the outer surface of the buckle. While buckles of this type have been previously proposed, the present buckle structure is particularly convenient to use and trouble-free in operation as well as being simple so as to be economical to manufacture and highly reliable in operation.

As disclosed in the following detailed description of a preferred embodiment of the invention, the tongue member fitted to one of the belt ends consists of a flat section having a slot adjacent to its extreme end which extends transversely to the length of the belt. The tongue is adapted to be inserted into the base of the other buckle member. The base consists of a flat bottom with a pair of upturned side walls. The side walls pivotably support a latching member having a lock section adapted to enter the slot in the tongue in order to retain the tongue within the base member. A spring biases the latch member into this downward, locked position and allows the latch member to be rocked into an unlocked position by the end of the tongue member as it is pressed into the buckle. When the latch member is in its closed position with its lock section extending into the slot in the tongue, any retracting force exerted on the tongue simply tends to urge the latch member further in its locking direction. In order to open the belt, the latch member is pivoted out of its locked position by depressing a pushbutton slidably supported in a cover member for the base. The cover member extends over the top and sides of the base and provides a slot at one end for the entrance of the tongue member. The pushbutton is mechanically connected to the latch member by a lever arm rotatably supported between the upturned sides of the base. The lever has one extending section that abuts an extreme end of the latch and another extending section which carries a cam shaped section that abuts the lower end of the pushbutton. The spring bias on the latch member is communicated through the lever to normally retain the pushbutton in its upward position. When a force is exerted on the pushbutton to move it downwardly the lever rotates about the axis of its pivotable suspension in the sides of the base to lift the end of the latch member, thereby retracting the locking section from the slot in the tongue. While the pushbutton is so depressed, the tongue may be with drawn from the buckle. The extension of the lever between its axis of rotation and contact with the button is several times longer than its extension between the axis of rotation and its contact with the latch so as to provide a mechanical advantage to the opening action and also require a relatively large button movement before opening will occur. The lever structure is such as to increase this mechanical advantage as the button moves downwardly, effectively increasing the distance through which the button must be moved to actuate the latch. The mechanical advantage tends to insure the buckle will open after it has been subjected to heavy stresses, such as might occur in an accident. It is an important safety feature since if the buckle would not open after an accident, the occupant of the seat might be trapped therein. The relatively large pushbutton movement before the buckle opens insures against accidental opening of the buckle member. The upper surface of the bottom is recessed within a surrounding ridge in the buckle top to provide additional assurance that an accidental force on the top will not depress the button.

It is therefore seen to be a primary object of the present invention to provide a simple and reliable construction for a belt retaining buckle wherein a spring biased latch member rotatably supported with respect to the buckle base has a locking sec-tion which enters a slot in the buckle tongue and retains it until released by a pushbutton which is slid'ably supported in the buckle cover.

Another object is to provide such a buckle wherein the connection between the pushbutton and the latch member takes the form of a lever of the first class wherein the length of the arm between the fulcrum of the lever and its contact with the button is appreciably longer than the distance between the fulcrum and the contact point of the arm with the latch.

Another object is to provide such a structure wherein a cam contour is interposed between the button and the contacting surface of the lever so as to increase the efficiency of the conversion of the motion of the but-ton into rotation of the lever.

Other objects, advantages and applications of the present invention will be made apparent by the following detailed description of a preferred. embodiment of the invention. The description makes reference to the accompanying drawings in which:

FIGURE 1 is a top view of a buckle formed in accordance with the present invention along with the ends of its associated belt webbings;

FIGURE 2 is an elevation sectional view through the structure of the buckle taken along line 22 of FIG- URE 1;

FIGURE 3 is a plan view of the buckle with the cover member removed;

FIGURE 4 is a perspective view of the buckle and the retracted tongue with the cover again removed for purposes of illustration;

FIGURE 5 is an elevation sectional view through the buckle assembly while the button is in a depressed condition taken substantially along line 22 of FIGURE 1; and

FIGURE 6 is a detailed section through the pushbutton taken along line 6-6 of FIGURE 5.

Referring to the drawings, the buckle of the present invention is applied at the ends of a pair of webbing sections 10 and 12. The opposite ends of the webbing section are appropriately connected to the frame of the vehicle in which the belt system is employed so that when the two buckle sections are joined together a closed loop is formed securely retaining the occupant in his seat. The belt section 12 is joined to a main buckle member 14 in a manner which will be subsequently described. The belt section 12 is joined to a tongue member, generally indicated at 1e which is adapted to be locked within the buckle 14.

The tongue section 16 is formed of a relatively thin,

fiat metal plate, generally rectangular in shape, and having a widened section 18 at one end] formed with a slot 20 across its width. A loop 22 is formed at the end of the belt 12 and is appropriately joined to the main belt section, as by sewing, in order to retain the tongue mem- 35 her 16 on the end of the belt 12. The forward end of the tongue 16 has rounded corners 24 and has a second, rectangular slot 26 formed across its width.

A main buckle member 14- is formed about a base member 28 which has a pair of opposed upturned sides 30 and 32 which extend generally normally to the base. The base member and sides are preferably stamped out of high tensile, alloy steel. At the end of the base member, adjacent to the belt (which will be termed the rear end of the base), the side walls and 32 are obliquely pierced at opposed points to form slots 34. A serrated roller 36, having a length slightly less than the distance between the interior opposed sides of the walls 30 and 32, is supported in the slots by means of extending rectangular tabs 38 which project from its ends into but not through the slots. The tabs 38 are shorter and thinner than the slots so that the roller 36 may slide along the slotsjThe base 28 has a section 40 punched out of its bottom which allows the belt 10 to be brought up through the hole 40*, brought around the roller 36, and returned through the slot. In this manner when a pull is exerted on the belt 10, the roller 36 tends to move downwardly in the slot 34 and thus lock the belt 10 to the buckle section 14- against retraction.

The forward end of the punched out section 40 is bent upwardly and forwardly into a tab 42 which acts as a stop for the forward end of the tongue 16 when that is inserted into the base. As may be best seen in FIGURE 2, the tongue is locked into the base by means of a latch member 44.

The latch member 44 is formed of a sheet of metal having a pair of upturned sides 46. The distance between the outer surfaces of the upturned sides 46 is slightly less than the distance between the internal surfaces of the sides 30 and 32 of the base so that the latch member may the supported between the sides 30 and 32 with its surfaces 46 adjacent to the interior sides of the members 30 and 32.

A shaft 48 has its opposite ends fixed within holes pierced in opposed points on the sides 30 and 32 adjacent to the forward ends thereof. The shaft extends laterally across the width of the base and passes through a pair of holes formed in the sides 46 of the latch so as to rotatably support the latch with respect to the base. A helical torsion spring 50 is wrapped about the shaft 48 just inside of one of the walls 46 of the latch and has one extending arm which abuts a tab 52 bent inwardly from the top edge of the side wall 30 of the base, the other arm resting in an appropriate depression in the edge of the center section of the latch 44. The coil urges the ends of the 1 spring 50 to move away from one another so as to exert a downward force on the rear end of the latch member tending to rotate it in a counter-clockwise direction as shown in FIGURE 4.

The latch member 44 has a forward section 58 which is bent generally upward with respect to the base 28, so that the tongue 16 may be easily inserted under the latch member by pressing it against the lower end of the section 5%. The latch member has a downwardly bent locking tab 60 pierced out of and extending from its intermediate section which is normally disposed with its lower end just above the base member 28. A rearwardly and upwardly extending tab 62 projects from the center of the rear of the latch member and is used to open the latch member as will be subsequently described.

The base is surrounded on its top and sides by a cover member generally indicated at preferably formed of plastic and being generally rectangular in shape with a closed top 72 and four downwardly projecting sides '74. The front side of the cover is cut away as at 75 to allow the tongue to be inserted in the buckle member and the remaining front of the cover prevents the tongue from being accidentally inserted over the top of the latch section 58 and giving a false latch condition. The cover passes over the side members of the base 30 and 32 and snaps thereon by means of a protrusion 76 which extends inwardly from the top sides and mates with recesses 78 formed on the rear ends of the side plates 30 and 32. The fit of the tabs in the recesses allows the cover to be pressed over the sides of the base member and locked in position and it may be removed for inspection by pulling the downwardly turned rear end of the cover 70 away from the sides 28 and 30.

A rectangular aperture 80 is formed in the top of the cover member adjacent to its front end. A plastic pushbutton 86 having outer dimensions which are complementary to the aperture 80 is disposed therein. The planar surface of the pushbutton 86 is surrounded by a downturned edge 88 and which fits within the side walls 84 of the aperture. As may be best seen in FIGURE 1, tabs 5*0 extend from the four corners of the sides of the pushbutton 86 in sideward directions and are journaled in slots 92 formed in the side surfaces of the downturned edge 84. These slots guide the pushbutton for vertical motion within the aperture 80 and the upper ends of the slots limit the upward movement of the pushbutton within the aperture.

The pushbutton is intended to normally be disposed just below its extreme upward position as shown in FIG- URE 2 and performs the function of releasing the lock section 60 of the latch 44 from the slot 26 and the tongue member 16 when the button is depressed. The space between the extreme upward position of the button and its normal position eliminates the possibility, of the button forcing the cover upwardly in the event of accidental forces pulling on the tongue 16. It is normally maintained in its upward position, and acts to lift the latch when depressed by means of a lever generally indicated at 100. The lever may be formed of heavy wire and includes a pair of sideward extending sections 102 which have their ends rotatably supported in holes formed in the side walls 30 and 32 so as to pivotably support the entire lever for rotation about the axis of the arms 102. The lever may alternatively be formed of fiat steel, in which event appropriately supported bushings (not shown) must be employed to rotatably journal its ends in the side walls. In

this manner, the sections 102 act as the fulcrum of the lever. One of the arms of the lever is formed by a rearwardly bent section 104 which comprises a continuation and connection between the two straight sections 102. The center section of this arm 104 rests directly beneath the extreme end of the tab 62 formed on the rear of the latch member. The second arm of the lever is formed by a loop 1&6 which is connected at two ends to the rearward edges of the arm 104 and projects rearwardly and upwardly therefrom, terminating in a transversely extending section 108. The section 108 is bent downwardly with respect to the main plane of the arms 106 in a general cam curve which is visible in the side views of FiG-URES 2 and 5.

As may be seen in FIGURE 5, when a force is exerted on the top of the pushbutton 86, it moves downwardly and its underside forces the arm 106 to rotate in a clockwise direction as viewed in FIGURES 2 and 6. The friction of the underside of the pushbutton on the arm 106 is minimized by the rounded cam shape of the arm which assists in the conversion of the downward linear motion of the pushbutton into a rotation of the lever. The rotation of the lever about its fulcrum, formed by the sections 102, as a result of the downward motion of the pushbutton, raises the arm 104 against the tab 62 as the arm 104 is rotated in a clockwise direction. This forces the latch member 44 to move about its support shaft 48, rotating the latch in a clockwise direction. As may be seen in FIGURE 6, this motion lifts the lock section 60 of the latch out of the slot 26 of the tongue allowing the tongue to be withdrawn from the buckle mechanism 14.

The rotational force exerted on the latch by the lever is several times greater than the downward force exerted on the button because of the mechanical advantage gained by virtue of the difference in distances between the ends of the two arms of the lever with respect to the fulcrum. This also necessitates a considerable downward motion of the button to lift the latch member out of the tongue, obviating the possibility of a slight accidental deflection of the pushbutton withdrawing the lock.

As the lever 100 is rotated in the clockwise direction as viewed in FIGURE 2, the distance from the arm 104 to the rotational axis 1112 (taken normally to the downward pushbutton motion) decreases, and the distance of the arm 108 to the rotational axis increases, raising the mechanical advantage of the lever and increasing the distance through which the button must move to actuate the latch. This minimizes the possibility of accidental opening by requiring a relatively high initial force, acting through a relatively long distance, to open the latch.

The ridge 82 which surrounds the pushbutton when it is at its upper position also minimizes the possibility of an accidental force energizing the release.

When the force is removed from the pushbutton, the spring 50 tends to uge the latch member to rotate in a counter-clockwise direction, in turn rotating the lever in that direction and lifting the arm 108 of the lever against the underside of the pushbutton, raising it into its normal upward locked position.

It is thus seen that the tongue may be easily looked in the buckle and is securely retained therein until a definite force, acting through a fairly large distance, depresses the pushbutton so as to rotate the latch out of its locked position.

Having thus described our invention, we claim:

1. A buckle for a seat belt, comprising: a base member; a latch supported for motion between two extreme positions with respect to the base member; a locking section on said latch member adapted to be disposed adjacent to the base member at one extreme of motion thereof; a pushbutton slidably supported for motion toward and away from said base member; a lever pivotably supported with respect to the base and having a first arm which projects from the axis of pivotation of said lever and contacts said latch member at a point separated from the axis of rotation of the latch member and a second extending arm which projects in a substantially opposite direction from said axis of pivotation and movably contacts the side of the pushbutton facing said base, whereby a motion of the pushbutton in the direction of the base will rotate the lever member and thereby move the latch member so as to transfer it away from the position wherein the locking section is adjacent to said base; and a tongue member having an aperture therein adapted to be inserted between the base member and the latch member so that said locking section engages the aperture.

2. The buckle of claim 1 wherein the latch member is pivotably supported with respect to the base about an axis that extends parallel to the base and the lever member is also pivotably supported with respect to the base about an axis that extends parallel to the base.

3. The buckle of claim 1 wherein the base has a pair of opposed upturned side members which journal both the latch member and the lever member for pivotable movement with respect to the base.

4. The buckle of claim 1 wherein a cover member is attached to the base so as to enclose said latch member and lever member between the base and the cover.

5. The buckle member of claim 3 wherein a cover member having a planar top and four downturned sides is connected to the base member by means of the upturned sides of the base member and said cover member has an aperture therein which supports and guides the pushbutton for movement toward and away from said base.

6. The buckle of claim 4 wherein the lever member has a pair of oppositely extending arms which have their ends journaled in the upturned sides of the base, said first arm projecting from the center of said pair of arms in a direction normally to said pair of arms, and said second arm projecting from the extreme end of the first arm in a direction generally toward said pair of arms and beyond them, so that the extreme ends of the first and second arms are on opposite sides of the axis of pivotation of the lever.

7. The buckle of claim 1 wherein. the distance between the center of the axis of pivotation of the lever and the end of the arm that contacts the pushbutton taklen normally to the pushbutton motion is greater than the distance between the axis of pivotation of the lever and the end of the arm that contacts the latch.

8. The buckle of claim 7 wherein the distance between the end of the lever arm which contacts the pushbutton and the axis of pivotation increases relative to the distance between the end of the lever arm which contacts the latch and the arms of pivotation as the pushbutton is depressed, thereby increasing the distance through which the button must move to actuate the latch.

References Cited UNITED STATES PATENTS 2,995,792 8/ 1961 Morton. 3,270,388 9/ 1966 Humphrey.

FOREIGN PATENTS 196,085 3/1908 Germany. 570,923 12/ 1957 Italy.

BERNARD A. GELAK, Primary Examiner. 

1. A BUCKLE FOR A SEAT BELT, COMPRISING: A BASE MEMBER; A LATCH SUPPORTED FOR MOTION BETWEEN TWO EXTREME POSITIONS WITH RESPECT TO THE BASE MEMBER; A LOCKING SECTION ON SAID LATCH MEMBER ADAPTED TO BE DISPOSED ADJACENT TO THE BASE MEMBER AT ONE EXTREME OF MOTION THEREOF; A PUSHBUTTON SLIDABLY SUPPORTED FOR MOTION TOWARD AND AWAY FROM SAID BASE MEMBER; A LEVER PIVOTABLY SUPPORTED WITH RESPECT TO THE BASE AND HAVING A FIRST ARM WHICH PROJECTS FROM THE AXIS OF PIVOTATION OF SAID LEVER AND CONTACTS SAID LATCH MEMBER AT A POINT SEPARATED FROM THE AXIS OF ROTATION OF THE LATCH MEMBER AND A SECOND EXTENDING ARM WHICH PROJECTS IN A SUBSTANTIALLY OPPOSITE DIRECTION FROM SAID AXIS OF PIVOTATION AND MOVABLY CONTACTS THE SIDE OF THE PUSHBUTTON FACING SAID BASE, WHEREBY A MOTION OF THE PUSHBUTTON IN THE DIRECTION OF THE BASE WILL ROTATE THE LEVER MEMBER AND THEREBY MOVE THE LATCH MEMBER SO AS TO TRANSFER IT AWAY FROM THE POSITION WHEREIN THE LOCKING SECTION IS ADJACENT TO SAID BASE; AND A TONGUE MEMBER HAVING AN APERTURE THEREIN ADAPTED TO BE INSERTED BETWEEN THE BASE MEMBER AND THE LATCH MEMBER SO THAT SAID LOCKING SECTION ENGAGES THE APERTURE. 